We recently heard some interesting stats for game studios, which came to us by way of a contact at Google:

Improving your Play Store rating from 3.3 stars to 4.1 stars is correlated, on average, with a gain of 150 percent in revenues.

Moreover, one of the best ways to achieve this improved rating is by optimising the speed and fluidity of your game, because 60 percent of four-star reviews mention this particular aspect of user experience.